First of all, if this is a new BAQ Report, consider using the new method
The big difference is that BAQ Reports run the BAQ (wide open) and then post-filter either with a CTE or in the .rdl on SSRS. While the new Method lets you join BAQs to BAQs together as well pass in BAQ @Parameters
More Info by @JeffLeBert the Godfather of SSRS:
https://www.epiusers.help/search?q=baq%20report%20%40JeffLeBert%20
If it is an existing one, you would start by modifying the BAQ that the BAQ Report uses, and adding your column to it. You should be able to find plenty of Filtering Case Studies on BAQ Reports, perhaps even better in the Epicor Application Help (Classic) or the Customizations User Guide with Pictures.